Plate cassette for platesetter

ABSTRACT

A plate cassette for a platesetter comprises a tray that receives and stores stacks of plates. Side frame members are located on opposed sides of the tray. These side frame members have tracks that engage with wheels of another plate cassette and wheels that engage with tracks of still another plate cassette. In this way, cassettes may be stacked and stored, one on top of each other. The wheel engagement strategy, between cassettes, however, allows individual cassettes to be rolled out, enabling access to the plate stack in the selected cassette&#39;s tray. A suction leak groove is formed in a surface of the tray. This provides for a suction leakage path for a picker, when the picker must grab typically the last plate in the stack and the plate is not full-sized. The suction grabbers that do not directly grab the plate do not adhere to the tray, allowing the picker to separate the plate from the tray. A slip sheet removal groove is also provided.

BACKGROUND OF THE INVENTION

[0001] Plates are typically large substrates that have been coated withphotosensitive or thermally-sensitive material layers. Depending on thetype of plate, they can be sensitive or insensitive to ambient light.The plates are usually used in commercial printing operations. For largerun applications, the substrates are fabricated from aluminum, althoughorganic substrates, such as polyester or paper, are also available forsmaller runs. Because of the composition, the plates can be somewhatheavy, especially in the context of a stack of relatively large plates.

[0002] Computer-to-plate printing systems are used to render digitallystored print content onto these printing plates. Typically, a computersystem is used to drive an imaging engine of a platesetter. The engineselectively exposes the surfaces of the plates. In a commonimplementation, the plate is fixed to the outside or inside of a drumand then scanned with a modulated laser source in a raster fashion.

[0003] Typically, one of two different strategies is used to feed theplates to the imaging engine. In the simplest case, an operator manuallyplaces individual plates into a feeder that then conveys the platesthrough a feed port to the drum scanner. This approach, however, hassome obvious drawbacks, since an operator must be dedicated to feedingthe plates. Moreover, the printing system must be housed within alight-safe environment, if the plates being used have any sensitivity toambient light. The alternative approach is to use a plate manager.

[0004] Plate managers typically house multiple cassettes. Each cassetteholds tens of plates in a stack. For example, in one commonimplementation, each cassette holds about thirty to fifty plates. Theplate manager selects plates from one of its cassettes and then feedsthe plates, automatically, into the imaging engine.

[0005] In these designs, cassettes are loaded into the plate manager onseparate tables. The tables are then raised and lowered inside themanager to bring the plates of a selected cassette into cooperation witha plate picker that grabs individual plates and feeds them to theimaging engine.

[0006] In some applications, the plates can be shipped and stored inthese cassettes. In other cases, the plates are shipped to the end userin a crate and then transferred to the cassettes by an operator.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to plate cassettes andspecifically improvements concerning functionality, usability, and formfactor of these cassettes.

[0008] In general, according to one aspect, the invention features platecassettes for platesetters. The cassettes comprise trays that receiveand store stacks of plates. Side frame members are located on opposedsides of these trays. These side frame members have tracks that engagewith wheels of another plate cassette and wheels that engage with tracksof still another plate cassette. In this way, the cassettes may bestacked and stored, one on top of each other. The wheel engagementstrategy between cassettes, however, allows individual cassettes to berolled out, enabling access to the plate stack in the selectedcassette's tray.

[0009] According to the present embodiment, a suction leak groove isformed in a surface of the tray. This provides for a suction leakagepath for a picker, when the picker is grabbing typically the last platein the stack and the plate is not full-sized. The suction grabbers thatdo not directly grab the plate do not adhere to the tray, allowing thepicker to separate the plate from the tray.

[0010] In specific implementations, edge guides may be provided in thetray. These may be slid along the guides in order to adjust to differentsized plate stacks.

[0011] In order to protect the stack of plates held in the tray, in thepresent embodiment, cover frame members are further provided on opposedsides of the trays. A cover then cooperates with these cover members toprotect plates in the tray.

[0012] In the preferred embodiment, the wheels are located on the bottomof each side frame member. This allows the cassette to be rolled by anoperator, in one example. This feature can be especially useful when theplate cassette holds a full stack of full-size plates, which can weighover 100 pounds or about 50 kilograms.

[0013] In this configuration, the tracks are located on the top of eachside frame member. Specifically, groove-shaped tracks are used in oneexample.

[0014] To align multiple cassettes, one on top of each other,registration features are preferably incorporated into the tracks. Thesecan be stops and/or bumps that are used to allow the operator to “feel”when the cassettes are properly stacked.

[0015] According to still further aspects of the present invention,support ledges can be provided on the cassette. These are used tocooperate with docking station arms that are used to engage and supportthe cassette, for example, in a plate manager.

[0016] In general, according to still another aspect, the inventionfeatures a plate cassette for a platesetter. It has a tray for receivinga stack of plates and a suction leak groove formed in a surface of thetray for providing a suction leak path for a picker, especially whengrabbing undersized plates that are held in the tray.

[0017] The above and other features of the invention including variousnovel details of construction and combinations of parts, and otheradvantages, will now be more particularly described with reference tothe accompanying drawings and pointed out in the claims. It will beunderstood that the particular method and device embodying the inventionare shown by way of illustration and not as a limitation of theinvention. The principles and features of this invention may be employedin various and numerous embodiments without departing from the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the accompanying drawings, reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale; emphasis has instead been placed upon illustratingthe principles of the invention. Of the drawings:

[0019]FIG. 1 is a perspective view of a plate cassette, according to thepresent invention, with its cover removed;

[0020]FIG. 2 is a perspective view of a plate cassette with its cover,according to the present invention;

[0021]FIG. 3 is a perspective view showing the bottom of the platecassette according to the present invention;

[0022]FIG. 4 is a close-up view showing the cassette wheels and supportledges according to the present invention; and

[0023]FIG. 5 is a perspective view of the plate cassette with a stack ofplates loaded in it, according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024]FIG. 1 shows a plate cassette that has been constructed accordingto the principles of the present invention.

[0025] Generally, the plate cassette comprises a tray 102, which has anannular outer sidewall 110 to thereby define a recess into which a stackof plates is loaded during operation.

[0026] In more detail, the tray 102 comprises a generally planar topsurface for supporting a stack of plates. A registration guide 105projects upward from the tray's surface; the stack of plates isregistered against this guide 105. Adjustable stack registration guides106 are movable to accommodate different size plates.

[0027] Specifically, movable stack registration guide 106-T engages atop of the plates. It has a thumbscrew, which when loosened allows theregistration guide 106-T to slide in its corresponding track 104-T. In asimilar vein, left and right stack registration guides 106-L, 106-R arealso adjustable by the loosening of a corresponding adjustment screws sothat they can slide in respective guide tracks 104-L, 104-R.

[0028] In order to allow the plate stack to be centered on the tray 102,a ruler 108 is provided extending laterally across the tray 102, at thefront.

[0029] The annular outer sidewall 110 comprises left and right sideframe members 112-L, 112-R. These side frame members project upward fromthe planar surface of the tray 102. According to the invention, eachside frame member comprises a track 114-L, 114-R for guiding the wheelsof another plate cassette. In the specific illustrated embodiment, thetracks 114-L, 114-R are located at the tops of the side frame members112L, 112R and comprise grooves in which the wheels of another cassetteride allowing stacked cassettes 100 to be moved or slide relative toeach other.

[0030] The outer sidewall 110 further comprises cover frame members112-B, 112-F. These similarly project up from the planar surface of thetray 102. The cover frame members 112-B, 112-F extend between the slideframe members 112-L, 112-R at the back and front of the plate cassette100.

[0031] Relevant to the discussion of the next figure is the fact thatthe cover frame members 112-B, 112-F have tops that are somewhat lowerthan the side frame members 112-L, 112-R. This is illustrated by thelips 116 between the higher side frame members 11 2-L, 11 2-R and thecover frame members 112-B, 112-F.

[0032]FIG. 2 shows the plate cassette with an optional cover 120.Specifically, a cover 120 sits on the cover frame members 112-B, 112-F.It specifically sits between the lips 116. In this way, the cover 120 isprimarily supported by the cover frame members 112-B, 112-F. It preventslight leakage between the cover 120 and the side frame members 112-L,112-R.

[0033] Best shown from the view of FIG. 2 are front support ledges130-LF and 130-RF. Note that a similar pair of support ledges are foundon the backside of the cassette 100. These ledges 130-LF, 130-RFcomprise cut-out regions that accept docking station arms to enable theautomated engagement and support of the plate cassette 100 in a platemanager, for example.

[0034] Further shown are wheels 140-R. These wheels 140-R are designedand positioned to cooperate with a track 114-R on another platecassette, located under the illustrated plate cassette 100. Thisconfiguration allows the plate cassettes to be stacked but still sliderelative to each other.

[0035]FIG. 3 shows the bottom of the plate cassette 100. The view showsall four of the support ledges 130-LF, 130-RF, 130-LB, 130-RB. Alsoshown is a reinforcing member 150. In one embodiment, the tray 102 andthe annular outer sidewall 110 are comprised of a plastic, such as afoamed or other molded plastic. As such, it may not be strong enough tosupport the sometimes heavy stack of plates. In the presentimplementation, a planar support member 150 is adhered to the bottomside of the tray 102 to increase the rigidity of the plate cassette 100.Presently, a honeycombed aluminum matrix is used.

[0036]FIG. 4 is a close-up view illustrating the support ledge 130-LB.Also shown is one of the wheels 140-L.

[0037] This close-up view further shows some of the features in thetracks 114. Specifically, in the illustrated track 114-L, a bump 160-Lis provided. This bump provides sensory feedback to the operator tofacilitate detection of when stacked cassettes are registered andaligned, one on top of each other. Specifically, when the wheels of acassette are riding in the track and that cassette is nearing fullinsertion, the operator will detect the cassette's wheels riding overthe bump 160-L. Further, to maintain the alignment of stacked cassettes100, a stop 162-L is provided to retain the cassettes in an alignedposition by preventing the wheels from continuing to roll in the track114-L.

[0038] Preferably, a similar bump 160-R and stop 162-R are provided inthe other track 114-R, which is not shown in this view.

[0039]FIG. 5 shows the plate cassette 100 loaded with a stack of plates10. The registration brackets 106-L, 106-R, 106-T are adjusted in theirrespective tracks 104-L, 104-R, 104-T to hold and maintain the plates 10in a stack configuration.

[0040] Another feature of the invention is appreciated with reference tothe location of suction ports 50, shown in phantom. This shows where thesuction ports of a picker would be located relative to the cassette 100and specifically, the plates 10 and the tray 102. As shown, some ofthese suction port locations are located over the plates 10. This allowsthe suction ports to engage and pick up the top plate in the stack 10.When less than full-sized plates are used as shown, some of the ports 50will miss the plates. In some cases, these suction ports would grab thetray 102, especially when picking the last plates in the stack 10. Itcould lead to unintended operation as the cassette 100 was picked up bythe plate picker.

[0041] According to the present invention, a suction leak groove 170 isprovided in the tray 102. This suction leak groove extends laterallyacross the tray 102. This groove 170 is a depressed portion in theotherwise planar surface of the tray 102. As a result, this will preventthe creation of a vacuum between the tray 102 and the plate picker,which will prevent the plate picker from unintentionally picking-up thecassette 100, allowing only the top plate in the stack 10 to be picked.

[0042] A second, slightly wider slip-sheet removal groove 172 alsoextends laterally across the tray 102 between the leak groove 170 andthe registration guide 105. This groove is also a depressed portion orrecess in the otherwise planar surface of the tray 102. It is providedto facilitate the removal of slip sheets for small plates.

[0043] Slip sheets are sometimes used to separate the plates in thestack 50. They can be removed using a set of rollers that engages thesheet and then is driven to pull the sheet off the stack of plates.Sometimes one slip sheet remains after the last plate has been removedfrom the cassette. The slip-sheet removal groove 172 prevents engagementbetween the rollers and the tray 102, especially for smaller plate slipsheets, thereby preventing tray movement when the rollers are driven andalso prevent wear to the rollers and tray.

[0044] While this invention has been particularly shown and describedwith references to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the scope of the inventionencompassed by the appended claims.

1. A plate cassette for a platesetter, comprising: a tray for receivinga stack of plates; side frame members on opposed sides of the tray;tracks on the side frame members that engage with wheels of anotherplate cassette; and wheels on the side frame members that engage withtracks of another plate cassette.
 2. A plate cassette as claimed inclaim 1, further comprising a suction leak groove formed in a surface ofthe tray for providing a suction leakage path for a picker.
 3. A platecassette as claimed in claim 1, further comprising guides that slide onthe tray for aligning the stack of plates.
 4. A plate cassette asclaimed in claim 1, further comprising: cover frame members on opposedsides of the tray; and a cover cooperating with the cover frame membersto protect plates in the tray.
 5. A plate cassette as claimed in claim4, wherein the cover engages side frame members upon closure.
 6. A platecassette as claimed in claim 1, wherein the wheels are located on abottom of each side frame member.
 7. A plate cassette as claimed inclaim 1, wherein the tracks are located on a top of each side framemember.
 8. A plate cassette as claimed in claim 7, wherein the wheelsare located on a bottom of each side frame member.
 9. A plate cassetteas claimed in claim 1, wherein the tracks comprise grooves for guidingthe wheels, the tracks being formed into each side frame member.
 10. Aplate cassette as claimed in claim 1, further comprising cassetteregistration features formed into at least one of the tracks foraligning the cassette to another plate cassette.
 11. A plate cassette asclaimed in claim 10, wherein the registration features comprise at leastone bump in one of the tracks that cooperates with the wheels of theother cassette.
 12. A plate cassette as claimed in claim 1, furthercomprising a reinforcing member attached to a bottom of the tray forincreasing the rigidity of the cassette.
 13. A plate cassette as claimedin claim 1, further comprising support ledges that cooperate withdocking station arms that engage and support the cassette.
 14. A platecassette as claimed in claim 13, wherein the ledges comprise cut-outregions for accepting the docking station arms.
 15. A plate cassette asclaimed in claim 1, further comprising a suction leak groove formed onin a surface of the tray for providing a suction leakage path for apicker.
 16. A plate cassette as claimed in claim 1, further comprising aslip-sheet removal groove formed in a surface of the tray for providingclearance between slip sheet rollers and the tray during removal of aslip sheet on the tray.
 17. A plate cassette for a platesetter,comprising: a tray for receiving a stack of plates; and a suction leakgroove formed on in a surface of the tray for providing a suctionleakage path for a picker.
 18. A plate cassette as claimed in claim 15,further comprising edge guides that slide on the tray for aligning thestack of plates.
 19. A plate cassette for a platesetter, comprising: atray for receiving a stack of plates; and a slip-sheet removal grooveformed in a surface of the tray for providing clearance between slipsheet rollers and the tray during removal of a slip sheet on the tray.20. A plate cassette as claimed in claim 15, further comprising edgeguides that slide on the tray for aligning the stack of plates.